The present invention relates to a stereoscopic display apparatus for displaying a stereoscopic image on the basis of three-dimensional data of an object or images of an object obtained by seeing the object from a plurality of visual directions and, more particularly, to a stereoscopic display apparatus by which a stereoscopic image can be seen in a whole range of 360.degree. by using a cylindrical screen.
Generally, in a stereoscopic display in medical service or a layout of articles, it is required that a target object can be observed by a plurality of persons at a least distance of distinguished vision from arbitrary directions. In a stereoscopic display apparatus of a double-eye type which is represented by a glasses system, however, since the stereoscopic image can be seen only at a predetermined position, the image cannot be observed from an arbitrary direction.. On the other hand, there is a stereoscopic display apparatus of a volume scanning type such that a device like a fan is rotated in the space and points are displayed in the space by a laser beam. In the display apparatus of the volume scanning type, the target object can be seen from an arbitrary direction. There is a problem, however, such that both of rear and front points are simultaneously seen, so that a problem on an image quality remains. A multiplex hologram such that a stereoscopic image can be observed from the directions of 360.degree. by using a cylindrical hologram is also known in addition to the above apparatus. According to the multiplex hologram, however, the developing work which is executed after an interference exposure was performed to a cylindrical surface of a dry plate is complicated and it takes five hours or longer to form such a hologram. Moreover, another cylindrical hologram has to be newly formed of every different display object.
A multiplex hologram using a cylindrical liquid crystal display as shown in FIG. 1 is considered. In FIG. 1, for example, a liquid crystal display is used as a phase display device 500. A one-dimensional phase distribution of each horizontal stripe region which is obtained by dividing a display stereoscopic body 520 in the vertical direction and seeing the divided portions is displayed on the phase display device 500, for instance, as shown by a phase distribution 530-i. A lenticular screen 510 in which a plurality of lenticular lenses each having a micro width are cylindrically arranged is provided around the cylindrical phase display device 500 in order to diffuse the modulated light in the vertical direction. In a state in which the one-dimensional phase distribution in the horizontal direction is displayed on the phase display device 500, for example, when a coherent reproduction light is irradiated from the lower direction, the reproduction light is modulated in accordance with a hologram phase distribution displayed by the phase display device 500. The modulated light is enlarged in the vertical direction by the lenticular screen 510 and is emitted. Thus, the display stereoscopic body 520 can be seen in the screen 510 by eyes 28-1 and 28-2 of the observer.
In the stereoscopic display apparatus using the cylindrical display device, however, although a difference object can be displayed by rewriting the holographic phase distribution, it is difficult to construct the phase display device in a curved shape along the cylindrical surface. It is, therefore, difficult to realize a rewritable stereoscopic display apparatus by which an object can be observed from the directions of 360.degree..